Process for n-monomethylating certain acyl or carbalkoxy nitro-p-phenylenediamines

ABSTRACT

N-MONOMETHYLATES CERTAIN ACYL OR CARBALKOXY MITRO-PPHENYLENEDIAMINE COMPOUNDS BY REACTING SAID NITRO-PPHENYLENDEIAMINE COMPOUNDS WITH A MIXTURE CONTAINING FORMALDEHYDE OR PARAFORMALDEHYDE AND SULFURIC ACIDS.

United States Patent Oflice 3,794,676 Patented Feb. 26, 1974 3,794,676PROCESS FOR N-MONOMETHYLATING CERTAIN ACYL R CARBALKOXYNITRO-P-PHENYLENE- DIAMINES Alexander Halasz, Norwalk, Conn., assignorto Clairol Incorporated, New York, NY. No Drawing. Original applicationMay 13, 1968, Ser. No. 728,786, now Patent No. 3,591,638. Divided andthis application Jan. 12, 1971, Ser. No. 105,953

Int. Cl. C07c 125/06 US. Cl. 260-471 C 7 Claims ABSTRACT OF THEDISCLOSURE N-monomethylates certain acyl or carbalkoxynitro-pphenylenediamine compounds by reacting saidnitro-pphenylenediamine compounds with a mixture containing formaldehydeor paraformaldehyde and sulfuric acids.

CROSS REFERENCE This application is a division of Application Ser. No.728,786 filed May 13, 1968 now Pat. No. 3,591,638 granted July 6, 1971.

This invention relates to a process for N-methylating nitroanilines, andmore particularly to a process for monomethylating the primary aminefunctional groups (NH of substituted and unsubstituted nitroanilines.The products made by the process of the present invention are useful asdyes and especially as hair dyes for dyeing human hair.

The N-methylnitroanilines wherein one amino hydrogen is replaced by asingle methyl group in one or more amino groups form a group ofcompounds which are useful in dyeing hair. However, the preparation ofcompounds of this character, in accordance with prior art methods,present a number of problems. The chief problem is that the prior artmethylation procedures have a great tendency to replace both aminohydrogens on the same nitrogen atom, and thus produce products which areto a large extent the tertiary amine products.

It has now been found that the monomethylation of the primary aminogroups of nitroanilines can be accomplished in good yield by using amixture of sulfuric acid with formaldehyde, or paraformaldehyde as themethylating agent.

It is accordingly an object of the present invention to provide aprocess for the N-monomethylation of nitroanilines containing freeprimary amino groups in which no more than one amine hydrogen on thesame amino nitrogn is replaced by a methyl group.

It is a further object of the preset invention to provide a process forthe N-monomethylation of nitrophenylenediamines containing at, least onefree primary amino group in which no more than one amine hydrogen on thesame amino nitrogen is replaced by a methyl group.

It is also an object of the present invention to provide certain novelnitro-p-phenylenediamine compounds which are useful in dyeing hair andcertain novel compositions containing the same.

Other and more detailed objects of this invention will be apparent fromthe following description and claims.

The use of a combination of formaldehyde and formic I acid to methylateamines is known in the prior'art. In this connection attention isdirected to the following:

(1) The Action of Formaldehyde on Amines and Amino Acids, HQT. Clarke,H. B. Gillespie and L.

Method, Walter L. Borkowsky and E. C. Wagner, J. Org.

Chem. 1952, p. 1128.

(3) Methylation of Amines with Formaldehyde, Organic Reactions, vol. V,p. 307 (By Maurice L. Moore).

These processes, however, are not concerned with the monomethylation ofnitroanilines.

German Pats. 376,013; 491,856; and 503,113 disclose the methylation ofcertain phenyl amines using formaldehyde in an acid medium in thepresence of zinc. These references are also not concerned withnitronilines, and the processes disclosed therein are not applicable tothe preparation of the products of interest in the present invention.The presence of zinc in the reaction mixture of these German patentswould result in the reduction of the nitro groups of the nitroanilinesused as starting materials in the present invention, and would defeatthe purpose of the present invention, i.e., to prepare methylatednitroanilines.

German Pat. 156,056 shows the monomethylation of a-aminoanthraquinonesusing a combination of formaldehyde and sulfuric acid. It also refers toGerman Pat. 80,520 showing a similar reaction for aliphatic diamines inwhich, however, the yields are very poor. The a-aminoanthraquinones are,obviously, far removed chemically from the nitroanilines employed in theprocess of this invention. The u aminoanthraquinones are very weak basesand are notcomparable to the nitroanilines. The former are so weakprobably because of hydrogen-bonding of the amino group to the quinonecarbonyl, that they do not even form salts with acids which are stablein aqueous medium. This is quite different from the amines of thebenzene series. Another difference is that the a-aminoanthraquinonesexchange their a-amino group with relative ease when heated with asecond amine at elevated temperatures. Consequently, this teaching withregard to the a-aminoanthraquinones would not suggest itself in aprocess which employes the amines of the benzene series.

The process of the present invention is applicable to a variety ofnitroanilines. This term is used herein in its generic sense to includethe simple and unsubstituted nitroanilines, such as ortho, meta andparanitroaniline, and the more complicated nitroanilines which carryother substituents in various places on the benzene ring. By way ofexample the nitroanilines may carry one or more of such substituents asnitro, alkoxy, halogen, alkyl, amino, alkylamino, dialkylamino,acylamino, and carbalkoxyamino, etc.

Illustratively, nitroanilines which may be used in accordance with thepresent invention may be described by the formula:

wherein:

Y=H, N02, alkoxy, alkyl, halogen, NH NHalkyl,

N(a'lky'l) NH'acyl or NHCOOalkyl,

Z H,'NO alkoxy, halogen or alkyl, at least one of X,

3 compounds of this class there may be mentioned compounds of formula:

II. NH,

wherein: R =H or alkyl, R =H, alkyl, acyl or carbalkoxy, i.e.

Z=H, alkoxy, halogen or alkyl;

procedure. This can be done by acetylating one of the the N0 group beingin position 2 or 3 on the benzene ring.

The alkyl moieties of the radicals described in the above Formulas I andH, e.g., alkyl, alkoxy, carbalkoxy,

general, however, these will be lower alkyl groups having from 1 toabout 6 carbon atoms. Thus, they may be such alkyl moieties or methyl,ethyl, n-propyl, iso-propyl, n-

butyl, n-pentyl, hexyl, etc.

The acyl moiety in the acyl radical per se or the radical NHacyl of theabove formulas may also vary. They may be aliphatic or aromaticradicals, e.g., acetyl, propionyl, butyryl, hexanoyl, benzoyl, toluoyl(o, m, or p), dimethylbenzoyl, etc. Ordinarily, the acyl radical will bea carboxy acyl radical having up to about 8 carbon atoms.

When Y or Z is halogen in Formula I or II above, it may be any of thehalogens including Cl, Br, I, F. Y

In carrying out the process of the present invention, the nitroanilineis preferably dissolved in the sulfuric acid. The formaldehyde orparaformaldehyde is then added to the sulfuric acid solution, and themixture maintained at an elevated temperature until the reaction isamino nitrogens or preparing the corresponding urethane or benzoylderivative. After the methylation reaction, the acyl group or thecarbalkoxy group may be hydrolyzed off leaving the free amino group.

Compounds prepared in accordance with the present lnvention can beemployed to prepare basic, neutral or acidic dye compositions and may beused in conjunction with oxidation dyes. Furthermore, they may likewisebe included in hair dyeing compositions which contain other directdyeing dyes that also may or may not contain an oxidation dye. A varietyof direct dyeing dyes are known 1n the prior art which are useful forthis purpose. They include other nitro dyes, azo dyes, anthraquinonedyes, etc. By way of illustration, any of the nitro dyes disclosed inthe following US. patents may be used in conjunction withthe presentnitro dyes: 2,750,326; 2,750,327; 3,088,877; 3,088,878 and 3,088,978.

The pH of the dye compositions made in accordance with the invention canvary from about 2.5 to 11. In the acid range the pH of about 3.5 to 6 issuitable. It is preferred, however, that the compositions be in thealkaline range, and particularly at a pH of about 7.5 to 10.

Any selected water-dispersible, compatible, alkalizing agent -(if it isdesired to have the compositions in the alkaline range) can be used togive the desired pH. The quantity of the alkalizing agent employed canvary over a wide range depending on the dye, particular alkalizing agentemployed and the desired pH. Illustratively, the alkalizing agent canvary from less than about 0.1% to about 10%, and preferably from about0.25% to about 5% by weight of the compositions.

Water-soluble surface-active agents can also be utilized in formulatingdyeing compositions of this invention. These can be anionic, non-ionicor cationic. The quantity of these materials contained in thecomposition can vary widely. Generally, however, it will constitute fromabout 0.25 to 15% by weight of the composition and preferably from about0.25 to 10% by weight of the comcompleted. The reaction can be carriedout in the temperature range of about 40 C. to-.120 C. The preferredtemperature range, however, is from about 50 C.-100 C. The final productis then recovered using any suitable recovery technique, depending uponthe particular final product.

The quantity of formaldehyde orparaformaldehyde used in the process ofthe present invention may vary somewhat depending upon the resultsdesired. Generally, the molar ratio of formaldehyde or paraformaldehydeto the nitroaniline used will be in the range of from about 3 to 10moles of the formaldehyde or paraformaldehyde to 1 mole of nitroaniline,and preferably in the range of about 3 to 5. Both anhydrous formaldehydeor paraformaldehyde may be used, or, if we prefer, aqueous formaldehyde(formalin). However, the quantity of water introduced may not be morethan 20% on the weight of the sulfuric acid, and preferably, thereaction medium should be as nearly as possible anhydrous. Similarly,the quantity of sulfuric acid employed in the reaction medium may alsovary but will usually be in the range of molar ratio of about 5 to 20moles of sulfuric acid to 1 mole of the nitroaniline and preferably inthe ratio of 10 to 1.

Where more than one free-primary amino group is "present in theparticular nitroaniline selected for reaction,

erably from about 0.5 to 5% by weight.

The tinctorially effective quantities of dyes in the dye compositions ofthis invention can also vary over a wide range, such as that of about0.01% to greater than about 5%, e.g., 10%, by weight of the composition,and preferably from about 0.01% to about 2% by weight. The water contentof the composition is ordinarily the major constituent and can vary overa wide range depending in large measure on the quantity of otheradditives. Thus,

' the water content can be as little as 10%, and preferably one of theamino hydrogens of each of the amino nitrofrom about 70% to 99%.

. The dyeing compositions of this invention can be prepared by theconventional methods used in the hair dyeing art. Thus, they can beprepared by dissolving or suspending the dye in water in the desiredconcentration. Water miscible organic solvents can be employed tofacilitate solution of the dye; in this event, the dye can be dissolvedfirst in the solvent and then diluted with water. The dispersion of thevarious ingredients can also be faciliatated by heating the compositionat temperatures varying from 40 C. to 0., either before dilution withwater or afterwards.

. The dyeing compositions of this invention can be applied to hair bytheconventional techniques used in the art. Illustratively, when appliedto living hair on the human head, the compositions can be applied to thehair with a brush, sponge, or other means of contact, such as dippinguntil the hair is properly saturated with the composition.

The reaction time or time of contact of the dyeing composition with thehair is not critical and can vary over a wide range used in the hairdyeing art, such as periods of about 5 minutes to about 2 hours, andpreferably from about 15 minutes to about 60 minutes. The dyeingtemperature can vary over wide limits as is conventional in the art.Thus, the dyeing temperature can vary from about room temperature, e.g.,about 20 C., to above about 60 C., and preferably from about 20 C. toabout 45 C.

The following examples are further illustrative of the presentinvention. It should be understood, however, that the invention is notlimited thereto.

EXAMPLE 1 Methylation of 2-nitro-p-phenylenediamine NH: NH-CH:

N02 ECHO N02 To 15.3 g. of 2-nitro-p-phenylenediamine, dissolved in 150g. 96% H 80 was added 24 g. paraformaldehyde. The mixture was heatedwith stirring on the water bath for 20 minutes, after which the reactionmixture was poured over ice and made alkaline with ammonia. The product,which separated, was dissolved in 300 ml. acetone. The acetone solutionwas then clarified, after which there was added to it ml. concentratedhydrochloric acid. The precipitated hydrochloride of the product wasfiltered off and washed on the filter with acetone and dried. The purehydrochloride (M.P. 25 C.25 1 C.) thus obtained was slurred in 300 ml.water and converted to the free base by addition of excess ammonia.After minutes stirring, dark violet crystals were filtered off, washedwith water and dried. 13 g. pure N ,N -dimethyl-2-nitro-p-phenylenediamine was obtained. The M.P. of 99 C.-l00 C. of thepure product is identical the M.P. of N ,N-dimethyl-2-nitro-p-phenylenediamine. The infrared spectra of therespective compounds are also identical. The nitrogen analysis of eachcompound is also the same. This compound dyes gray and bleached hair astrong violet shade.

NH-CH:

EXAMPLE 2 Methylation of o-nitroaniline NHz HNCH:

N02 H C H 0 N02 HzS0 Methylation of m-nitroaniline HNCHa NH: 1 @NOZ@4102 The process of Example 1 was followed, excepting that in placeZ-nitro-p-phenylenediamine, an equivalent amount of m-nitroaniline wasemployed. The product recovered is N-methyl-m-nitroaniline.

6 EXAMPLE 4 Methylation of p-nitroaniline NH: HNCH;

HCHO

The process of Example 1 was followed, excepting that in place of2-nitro-p-phenylenediamine, an equivalent amount of p-nitroaniline wasemployed. The product re covered is N-methyl-p-nitroaniline.

EXAMPLE 5 Methylation of dinitroaniline NH; HN-CH;

The process of Example 1 was followed, excepting that in place ofZ-nitro-p-phenylenediamine, an equivalent amount of 2,4-dinitroanilineis utilized. The product recovered is N-methyl-2,4-dinitroaniline.

EXAMPLE 6 Methylation of 4-methoxy-2-nitroaniline NH, HNCHa @NO: CH

The process of Example 1 was followed, excepting that in place of2-nitro-p-phenylenediamine, 4-methoxy-2- nitroaniline is utilized. Theproduct recovered is N-methyl- 4-methoxy-2-nitroaniline.

EXAMPLE 7 Methylation of N benzoyl 2-nitro-p-phenylenediamine andpreparation of N methyl-Z-nitro-p-phenylenediamine I O CH;

To 15.3 g. 2-nitro-p-phenylenediamine, 9 g. NaHCO and 300 ml. acetonewere added to 14 g. benzoyl chloride, and the mixture was heated atreflux for one hour. There is obtained a very pure N-benZoyl-2-nitro-p-phenylenedi amine, M.P. 230 C.-234 C.

12.5 g. N -benzoyl-Z-nitro-p-phenylenediamine was dissolved in 100 ml.conc. H at room temperature with stirring. The solution was then heatedto 50 C., and over a period of one hour, 30 ml. 37% aqueous formaldehydewas added dropwise. The mixture was maintained at 50- 55 C. for anadditional 4 hours, after which it was poured into ice water. Thecrystals of N -methyl-N -benzoyl-2- nitro-p phenylenediamine whichprecipitated were orange and had a M.P. of 167-70 C. The crystals werehydrolyzed with 80 ml. 85% H 80 for 6 hours on a water bath.

The mixture was then poured onto ice, made alkaline with ammonia,filtered and washed. There was obtained 4.4 g. ofN-methyl-2-nitro-p-phenylenediamine, M.P. 107-108 C.

EXAMPLE 8 Methylation of N -acetyl-2-nitro-p-phenylenediamine andpreparation of N -methyl-2-nitro-p-phenylenediamine 19.5 parts of N-acetyl-2-nitro p phenylenediamine (prepared by reacting 1 part aceticanhydride with 1 part 2-nitro-p-phenylenediamine) was dissolved in 100parts of 96% H 80 at room temperature. The mixture is then heated to 50C. on a water bath, and 50 parts 37% aqueous formaldehyde is addeddropwise for one hour. Care was taken not to go beyond 55 C. Afteraddition, the reaction mixture was maintained at 55 C. for 2 hours andthen poured into ice water. The N -methyl-N-acetyl-2-nitro-p-phenylenediamine separates as crystals, M.P. at 147C.149" C. This was hydrolyzed with 80% H 80 at 95 C.100 C. There wasobtained 8.5 parts N -methyl-2-nitro-p-phenylenediamine.

EXAMPLE 9 Methylation of the urethane of 2-nitro-p-phenylenediamine andpreparation of N -methyl-2-nitro-p-phenylenediamine N H: Hz

N02 N01 C I NH: HNCOOC1H5 HNCH: HNCH;

NO: N02

----- hydrolysis I l HNCOOCzHs NE:

76.5 g. of 2-nitro-p-phenylenediamine, 45 g. sodium acetate and 500 ml.ethanol were heated at reflux and 5 6 g. ethyl chloroformate was droppedin the mass. After 1 hour, the reaction mixture was poured over icewater and filtered. There was obtained 88 g. of reaction product, whichafter recrystallization from water, had a M.P. of 129 C.l30" C.

11 g. of the urethane which was thus obtained and 100 g. H SO wasstirred until solution took place. Over a period of 1 hour, 35 m1. of a37% formaldehyde solution was added dropwise to the mixture. Thetemperature was maintained at 50 C.-60 C., the mixture stirred at thistemperature for an additional 4 hours and then poured into 600 ml. icewater. The product which separated was dissolved in acetone, filtered,and the acetone solution was evaporated. 12.5 g. of the urethane of N-methyl-Z-nitro-p-phenylenediamine was obtained. This NO: NO:

paraformaldehyde Hz S O 4 NH: HNCH;

To 15 g. N -isopropyl-2-nitro-p-phenylenediamine was added 100 g. cone.H 80 and the mixture stirred and heated on a water bath untildissolution occurred. After the temperature reached 65 C., there wasadded at once 15 g. paraformaldehyde. The mixture was heated to C. andkept at this temperature for 30 minutes, after which the reactionmixture was poured over ice and made alkaline with ammonia. Theprecipitate was filtered off and dissolved in 400 m1. acetone. Theacetone solution was filtered again to separate salt or otherimpurities. To the acetone solution was added 20 ml. cone. HCl. Thehydrochloride, which was formed, was filtered off and treated withaqueous ammonia to regenerate the free base. Yield was 7.5 g. The N-isopropyl-N -methyl-2-nitro-pphenylenediamine was obtained, has a M.P.of 79 C.- 81 C., and is a dark violet color. The nitrogen analysiscorresponded to the formula:

/CH3 IIIHCH NH-CH3 EXAMPLE 11 Methylation ofS-methoxy-Z-nitro-p-phenylenediamine NH: Nt tcn,

paraformaldehyde onto HIS 0. Cmo

NH: HNCHa 13 g. of 5-methoxy-2-nitro-p-phenylenediamine was dissolved bystirring in m1. H 80 at 40 C. To this solution was added 15 g.paraformaldehyde, and the mixture heated at 100 C. for 15 minutes, afterwhich the reaction mixture was poured over ice. After addition ofammonia, to make it alkaline, the mixture was filtered, and the filtercake washed, dried and recrystallized from benzene. There was obtained 3g. pure N ,N -dimethyl 5-methoxy-2-nitro-p-phenylenediamine as dark redcrystals of M.P. 153 C.-156 C.

EXAMPLE 12 Methylation of 5-chloro-2-nitro-p-phenylenediamine NH:HITICH:

paraformaldehyde 01 Has 0 01 NH: HNCH;

4 g. of 5-chloro-2-nitro-p-phenylenediamine was dissolved in 50 g. of H80 The solution was heated with stirring, and at 60 C., there was added6 g. paraformaldehyde. After heating at 95-100- C. on the water bath for2 hours, the mixture was poured into ice water. The solution was madealkaline with ammonia and the dark crystals which separated out werefiltered oif, washed with water and recrystallized for ethanol. Therewas obtained 2 g. dark violet crystals, pure chromatographically, M.P.170 C.-171 C. The analysis for C1 and N corresponded to N ,N-dimethyl-2-nitro-5-chloro-p-phenylenediamine.

EXAMPLE 13 Methylation of S-methyl-Z-nitro-p-phenylenediamine NH: HNCH;

paraformaldehyde N02 on. H2304 on.

NH: HNCH:

To 5 g. of 5-methyl-2-nitro-p-phenylenediamine dissolved in 50 ml. conc.H SO was added 8 g. paraformaldehyde. The mixture was heated on thewater bath for 5 hours and poured over ice. After stirring for sometime, the product was filtered 01f, washed with water, dried andrecrystallized for ethanol. The N ,N -dimethyl-2-nitro-5-methyl-p-phenylenediamine was obtained as dark red crystals, melting at144 C.14-6 C.

EXAMPLE 13A Monomethylation of 1-amino-3-nitro-4-fluorobenzene NH:IIQ'HCHQ paraformaldehyde NO1 H2304 N02 18.9 g. of 1-amino-3 nitro 4fluorobenzene was dissolved in 150 g. concentrated H 80 at roomtemperature. To this solution was added 30 g. paraformaldehyde and thewhole mixture heated on a water bath for 2 hours and 15 minutes. Thereaction mixture was then poured on ice, neutralized with amonia and thereaction product extracted with ethyl acetate. The ethyl acetatesolution was added to charcoal and then filtered. The filtrate yielded18.8 g. of 1-methylamino-3-nitro-4-fluorobenzene.

EXAMPLE 13B Monomethylation of 1-amino-2-nitro-4-methoxybenzene ITIHQNHCHa EXAMPLE l4 Dyeing hair with N,N*-dimethyl-2-nitro-pphenylenediamine One gram N N-dimethyl-Z-nitro-p-phenylenediamine was dissolved in a mixture of 20ml. isopropanol, about 200 ml. of water, 2 g. of monoethanolamine, 1 g.of triethanolamine, 1 g. of polyacrylic acid and 1 g. of

rubfast and not removable by washing with soap and water.

EXAMPLE 15 Dyeing hair with N -isopropyl-N-methyl-2-nitro-pphenylenediamine About 2 grams of N isopropyl-N-methyl-Z-nitro-pphenylenediamine was dissolved in about 17 g. ofisopropanol and then 200 g. of water was added with stirring to preparea solution. To this solution there were added 2 grams ofmonoethanolamine, 1 gram of triethanolamine and about 3 g. of Carbopol934 (a polycarboxylated vinyl resin, made by B. F. Goodrich & Co.). Themixture was thoroughly agitated. This composition was then poured intothe hair at the temperature of about 30 C. and permitted to remain onthe hair for 30 minutes, after which time it was washed out. The hairwas dyed to a blue violet color.

EXAMPLE 16 Dyeing hair with N ,N-dimethyl-Z-nitro-5-chloro-pphenylenediamine A dyeing composition wasprepared by dissolving 5 g. of N N-dimethyl-2-nitro-5-chloro-p-phenylenediamine in 50 g. of ethanol at 50C. The ethanol solution of the dye was then added 'with stirring to amixture containing 500 g. of water, 10 g. of diethanolamine and 1 g. ofagar agar as a thickener. The mixture was then heated to a temperatureof about 30 C. 37 C. and applied to the hair by simply pouring themixture over the hair. The dyeing mixture was left on the hair for 20minutes and then was rinsed out with Water. The hair was dyed darkviolet color without scalp staining.

EXAMPLE 17 Dyeing hair with N ,-N-dimethy1-2-nitro-S-methoxy-pphenylenediamine 5 parts of N N-dimethyl-2-nitro-5-methoxy-pphenylenediamine was admixed with 5 partsof isopropanol, 970 parts of water, 10 parts of monoethanolamine and 10parts of methylcellulose. This mixture was dissolved by stirring atabout 50 C., then permitted to cool to the ambient temperature of about33 C. and finally poured over gray hair on the human head. Thecomposition was permitted to remain on the hair for about 25 minutes,after which time, the hair was washed and thoroughly rinsed with water.The hair was dyed a bluish red color.

EXAMPLE 18 Dyeing hair with N ,Ndimethyl-2-nitro-5-methyl-pphenylenediamine 1 g. of N ,N-dimethyl-Z-nitro-5-methyl-p-phenylenediamine was dissolved in a mixtureof 20 ml. isopropanol, about 200 ml. water, 2 grams monoethanolamine, 1gram of triethanolamine, 1 gram polyacrylic acid and 1 gram glycerol at50 C. This composition was heated to about 35 C.-37 C. and then appliedto gray hair. After about 20 minutes, the hair was thoroughly rinsed andwashed with soap and water. The hair was colored bluish red and theresulting shade was rubfast and not removable by washing with soap andwater.

Although the invention has been described with reference to specificforms thereof, it will be understood that many changes and modificationsmay be made without departing from the spirit of this invention.

I 1 What is claimed is: 1. A process for N-monomethylating anitro-p-phenyllenediamine compound of formula:

R NRl to replace one amine hydrogen of the -NH group in the number 1position with a methyl group which comprises reacting saidnitro-p-phenylenediamine compound with a mixture containing formaldehydeor paraformaldehyde and sulfuric acid; the molar quantity offormaldehyde or paraformaldehyde employed being adequate to replace saidamine hydrogen with a methyl group; wherein:

R is hydrogen or alkyl having from 1 to 6 carbon atoms; R is selectedfrom the group consisting of an alkanoyl having 1 to 8 carbon atoms,benzoyl, m-, or ptoluoyl or dimethylbenzoyl or carbalkoxy having from 1to 6 carbon atoms; Z is hydrogen, alkoxy having 1 to 6 carbon atoms,

halogen, or alkyl having 1 to 6 carbon atoms; the group -N0 being in the2 or 3 position. 2. A process according to claim 1 wherein the reactionis carried out at a temparature in the range of about 40 C. to 120 C.

3. A process according to claim 2 wherein the reaction temperature is inthe range of about C. to C.

4. A process according to claim 2 wherein the molar ratio offormaldehyde or paraformaldehyde to 'said nitrop-phenylenediaminecompound is in the range of from about 3 to 10 moles of formaldehyde orparaformaldehyde to 1 mole of the said nitro-p-phenylenediaminecompound, and the molar ratio of sulfuric acid to saidnitrop-phenylenediamine compound is in the range of 5 to 20 moles ofsulfuric acid to 1 mole of said nitro-p-phenylenediamine compound.

5. A process according to claim 4 wherein said nitro-pphenylenediaminecompound is N -benzoyl 2 nitro-pphenylenediamine.

6. A process according to claim 4 wherein said nitrop-phenylenediaminecompound is N -acetyl-2 nitro pphenylenediamine.

7. A process according to claim 4 wherein said nitro-pphenylenediaminecompound is the urethane of Z-nitro-pphenylenediamine.

References Cited Royals, E. B, Advanced Organic Chemistry (1961) pub. byPrentice-Hall, Inc. (QDZS M168 C.6) page 649 relied on.

LORRAINE A. WEINBERNER, Primary Emaminer L. A. THAXTON, AssistantExaminer -U.S. Cl.X.R.

